Polyether polyols suitable for flexible polyurethane foam prepared by co-initiation of aqueous solutions of solid polyhydroxyl initiators

ABSTRACT

Polyoxyalkylene polyether polyols suitable for preparation of flexible polyurethane foams are prepared by oxyalkylating an aqueous solution of one or more polyhydric, hydroxyl-functional solid initiators under conditions where both water as well as initiator are oxyalkylated. The polyols have calculated functionalities of between about 2.2 and 4.0 and hydroxyl numbers in the range of 10 to 180. The polyols may be used to prepare soft, high resiliency polyurethane flexible foams at low isocyanate indexes.

This is a division of application Ser. No. 08/507,102 filed Jul. 26, 1995 now allowed as U.S. Pat. No. 5,596,059.

Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified.

EXAMPLE 1

A polyoxyalkylene polyether polyol is prepared in a two-stage process using a 70/30 weight percent syrup of sorbitol/water as the initiator, having a calculated average functionality of 2.75. Potassium hydroxide oxyalkylation catalyst in flake form is added at 120° C. in such amount that the first stage product contains 0.25 weight percent KOH. A vacuum of c.a. 1-3 psia is applied to the system prior to heating up. Propylene oxide is added and the initiator mixture oxyalkylated at c.a. 117° C. to form a c.a. 255 hydroxyl number intermediate, first stage product.

To a portion of the first stage product is added additional KOH prior to a second oxyalkylation to raise the KOH concentration to 0.34 weight percent based on the final product weight. Oxyalkylation is conducted with a 86/14 mixture of propylene oxide and ethylene oxide at 105° C. to form a final product having a hydroxyl number of c.a. 56 and an estimated functionality of 2.5. Basic catalyst residues are removed by conventional treatment. To the polyether polyol product is added a conventional antioxidant stabilizer package. The product has an APHA color of 25 and a viscosity of c.a. 440 cks at 25° C. This polyol is designated as "Polyol A".

EXAMPLE 2

The procedure of Example 1 is followed, but prior to oxyalkylation the sorbitol concentration in the initiator mixture is raised to yield an 88/12 weight ratio of sorbitol/water. The polyol product has a calculated functionality of 3.7 and an estimated functionality of about 3.2, and a hydroxyl number of 56. This polyol is designated as "Polyol B".

EXAMPLES 3 TO 8 AND COMPARATIVE EXAMPLES 3C TO 8C

A series of nominal 1.8 pcf polyurethane flexible foams are prepared in bench foaming tests employing constant levels of tin and amine catalysts. The tin catalyst is T-9 (dibutyltindilaurate) at 0.2 parts per 100 parts polyol, and the amine catalyst A-133 (bis(2-dimethylaminoethyl)ether, active component) at 0.15 parts per 100 parts polyol. Polyol A is the polyol of Example 1 and contained 0.01 parts water. Polyol C is a prior art, glycerine initiated polyol having a hydroxyl number of 56, a measured functionality of 2.7, and a random internal ethylene oxide content of c.a. 8.5 weight percent. Polyol C contains 0.08 weight percent water. Each foam formulation contains 3.8 parts water per 100 parts polyol (not including water contained in the polyol), and employs 0.600 parts of a foam stabilizing silicone surfactant L-620 available from OSi Chemicals. The foams were prepared by reacting the polyol component described above, with toluene diisocyanate (TDI) at isocyanate indices of from 110 to 85. The results are presented in Table 1. The actual isocyanate index for each foam, taking into account all water, is in parentheses.

                  TABLE 1     ______________________________________     EXAMPLE  3C      3       4C    4     5C    5     ______________________________________     POLYOL C 100.000         100.000     100.000     POLYOL A         100.000       100.000     100.000     TDI      49.970  49.970  45.430                                    45.430                                          43.150                                                43.150     INDEX    110.000 110.000 100.000                                    100.000                                          95.000                                                95.000              (108.2) (109.8) (98.3)                                    (99.8)                                          (93.4)                                                (94.8)     PHYSICAL     PROPERTIES:     DENSITY  1.540   1.590   1.660 1.720 1.720 1.740     RESILIENCY              28.000  28.000  30.000                                    30.000                                          33.000                                                32.000     POROSITY 3.040   3.510   3.240 3.210 4.700 5.440     IFD.sub.-- THICK              4.060   4.060   4.070 4.090 4.080 4.080     IFD.sub.-- 25%              47.550  45.670  44.470                                    44.550                                          38.700                                                36.080     IFD.sub.-- 65%              93.300  91.130  88.280                                    89.100                                          76.950                                                71.780     IFD.sub.-- 25%.sub.-- RT              33.750  32.850  33.080                                    33.220                                          29.630                                                27.750     RETURN.sub.--              70.980  71.920  74.370                                    74.580                                          76.550                                                76.920     VAL     IFD.sub.-- 65/25              1.960   2.000   1.980 2.000 1.990 1.990     TENSILE  13.070  12.220  13.150                                    10.840                                          13.740                                                12.460     ELON-    144.090 139.740 161.270                                    122.250                                          230.840                                                200.540     GATION     TEAR     1.140   1.070   1.330 1.140 1.800 2.560     COMP.sub.-- 90%              3.240   2.570   2.940 2.810 2.100 2.030     HA.sub.-- COMP.sub.--              4.590   4.40    3.230 4.000 2.190 3.120     75     WET.sub.-- SET.sub.--              2.480   2.740   2.200 2.350 .930  1.190     50     ______________________________________     EXAMPLE  6C      6       7C    7     8C    8     ______________________________________     POLYOL C 100.000         100.000     100.000     POLYOL A         100.000       100.000     100.000     TDI      40.880  40.880  38.610                                    38.610                                          36.340                                                36.340     INDEX    90.000  90.000  85.000                                    85.000                                          80.000                                                80.000              (88.5)  (89.8)  (83.6)                                    (84.8)                                          (78.7)                                                (79.8)     PHYSICAL     PROPERTIES:     DENSITY  Split   1.740   Split 1.760 Split Split     RESILIENCY       32.000        33.000     POROSITY         4.990         5.290     IFD.sub.-- THICK 4.050         4.070     IFD.sub.-- 25%   33.080        32.330     IFD.sub.-- 65%   67.800        65.700     IFD.sub.-- 25%.sub.-- RT                      25.270        24.830     RETURN.sub.--    76.420        76.800     VAL     IFD.sub.-- 65/25 2.050         2.030     TENSILE          13.030        13.400     ELON-            213.660       239.660     GATION     TEAR             1.890         1.790     COMP.sub.-- 90%  1.690         2.570     HA.sub.-- COMP.sub.--                      3.450         3.440     75     WET.sub.-- SET.sub.--                      3.970         3.210     50     ______________________________________

Table 1 indicates that physical properties of water-blown polyurethane foams prepared from the sorbitol/water initiated polyols of the subject invention (Polyol A) surprisingly are quite similar to those derived from a similar, glycerine initiated polyol (Polyol C) despite the fact that the latter contains nearly all trifunctional species (plus propylene oxide-derived monol), while the subject polyol, in addition to monol, is a mixture of species having nominal functionalities of two and six. In the bench scale tests presented in Table 1, the ability to formulate at lower index without splitting is particularly surprising, and may offer the ability to utilize less of the more expensive isocyanate component and/or may signify wider formulating and processing latitude. The foams prepared from the sorbitol/water initiator blends were also somewhat softer (note 25% ILD) and of slightly higher density than the foams prepared from glycerine-initiated polyols. The difference in softness may be due to the lower average (measured) functionality (2.4 versus 2.7) of the sorbitol/water polyol.

EXAMPLES 9 TO 13 AND COMPARATIVE EXAMPLES 9C AND 13C

Water-blown polyurethane flexible foams were prepared with TDI at an isocyanate index of 105 with constant levels of amine catalyst and tin catalyst ranging from 0.14 to 0.18 parts per 100 parts polyol. Polyol A (Example 1) and Polyol B (Example 2) were used alone and in blends, and compared to similar glycerine-initiated polyols, Polyol C (previously described) and Polyol D, a glycerine-initiated, epoxy resin modified polyol having an actual functionality of about 3.2 and a hydroxyl number of 56, containing random oxypropylene and oxyethylene moieties in a ratio of 85/15. The formulations and physical properties are presented in Table 2. The dramatic similarity between the sorbitol/water-initiated polyols and glycerine-initiated polyols of similar functionality is apparent.

                                      TABLE 2     __________________________________________________________________________     EXAMPLE      9C   9    10   11   12   13   13C     __________________________________________________________________________     POLYOL B (88/12)  100  75   50   25     POLYOL A (70/30)       25   50   75   100     POLYOL C                                   100     POLYOL D     100     WATER        3.8  3.8  3.8  3.8  3.8  3.8  3.8     A-133        0.2  0.2  0.2  0.2  0.2  0.2  0.2     T-9          0.14 0.14 0.14 0.18 0.18 0.18 0.18     L-620        0.6  0.6  0.6  0.6  0.6  0.6  0.6     TDI          47.7 47.7 47.7 47.7 47.7 47.7 47.7     INDEX        105  105  105  105  105  105  105     PHYSICAL PROPERTIES:     DENSITY      1.69 1.78 1.74 1.67 1.7  1.59 1.63     RESILIENCY   30   32   30   32   34   37   33     AIR FLOW     4.27 3.55 3.5  4.24 4.52 5.96 5.33     IFD.sub.-- THICK                  4.06 4.05 4.04 4.01 4.01 3.99 4.02     IFD.sub.-- 25%                  48.07                       49.79                            48.96                                 43.13                                      40.88                                           32.55                                                32.17     IFD.sub.-- 65%                  91.03                       96.07                            91.72                                 83.03                                      79.95                                           65.93                                                64.72     RETURN.sub.-- VAL                  71.78                       73.11                            71.25                                 70.43                                      73.03                                           72.58                                                74.59     IFD.sub.-- 65/25                  1.89 1.93 1.87 1.93 1.96 2.03 2.01     TENSILE      11.48                       9.4  10.62                                 10.96                                      7.52 12.3 12.23     ELONGATION   135.6                       97.14                            114.04                                 131.25                                      96.98                                           209.42                                                222.4     TEAR         0.99 0.67 0.76 1.07 1.17 1.52 2.3     COMP.sub.-- 90%                  3.36 2.74 3.19 2.94 3.2  4.21 4.42     WET.sub.-- SET.sub.-- 50                  3.19 3.03 3.19 2.43 2.51 3.83 3.59     __________________________________________________________________________

EXAMPLES 14 TO 19 AND COMPARATIVE EXAMPLES 14C TO 19C

A series of water-blown polyurethane foams of 1.7 lb/ft³ nominal density were prepared from the polyol of Example 1 (Polyol A) and a similar glycerine-initiated polyol (Polyol C) at various levels of tin catalyst to assess processing latitude, at an isocyanate index of 105. The foams prepared from the sorbitol/water-initiated polyols displayed excellent processing latitude and in general, good overall performance properties. The formulations and physical properties are presented in Tables 3 and 4.

                  TABLE 3     ______________________________________     EXAMPLE  14      14C     15    15C   16    16C     ______________________________________     POLYOL A 100             100         100     POLYOL C         100           100         100     WATER    3.8     3.8     3.8   3.8   3.8   3.8     WATER,   --      3.87    --    3.87  --    3.87     COR.     A-133    0.15    0.15    0.15  0.15  0.15  0.15     T-9      0.2     0.2     0.15  0.15  0.25  0.25     L-620    0.6     0.6     0.6   0.6   0.6   0.6     TDI      47.7    47.7    47.7  47.7  47.7  47.7     INDEX    105     105     105   105   105   105     PHYSICAL     PROPERTIES:     BLOW OFF 116     115     130   135   109   104     SETTLE % 0.81    0.89    1.98  1.19  1.48  0.79     DENSITY  1.65    1.57    1.61  1.54  1.57  1.47     DENSITY, --      1.6     --    1.57  --    1.5     COR.     RESILIENCY              46      33      31    33    35    34     AIR FLOW 4.23    3.14    6.11  6     3.34  2.07     IFD.sub.-- THICK              4.07    4.08    4.15  4.1   4.09  4.11     IFD.sub.-- 25%              44.66   50.43   39.67 43.31 44.76 49.54     IFD.sub.-- 65%              86.73   93.03   77.39 82    83.25 89.7     RETURN.sub.--              72.26   68.45   71.52 68.64 69.29 67.52     VAL     IFD.sub.-- 65/25              1.94    1.84    1.95  1.89  1.86  1.81     TENSILE  11.57   12.1    11.31 12.04 13.14 14.32     ELON-    117.68  113.55  135.09                                    130.68                                          148.13                                                147.83     GATION     TEAR     1.12    1.16    1.23  1.11  1.35  1.33     COMP.sub.-- 90%              2.57    2.56    2.58  1.98  3.21  3.4     HA.sub.-- COMP.sub.--              3.77    3.61    3.51  3.52  3.75  3.83     75     WET.sub.-- SET.sub.--              2.38    2.46    2.36  2.21  2.42  2.73     50     ______________________________________

                  TABLE 4     ______________________________________     EXAMPLE  17      17C     18    18C   19    19C     ______________________________________     POLYOL A 100             100         100     POLYOL C         100           100         100     WATER    3.8     3.8     3.8   3.8   3.8   3.8     WATER,   --      3.87    --    3.8   --    3.8     COR.     A-133    0.15    0.15    0.2   0.2   0.2   0.2     T-9      0.2     0.2     0.14  0.14  0.18  0.18     L-620    0.6     0.6     0.6   0.6   0.6   0.6     TDI      47.7    47.7    47.7  47.7  47.7  47.7     INDEX    105     105     105   105   105   105     PHYSICAL     PROPERTIES:     BLOW OFF                 134   122   114   110     SETTLE % 0.56    0.17    0.64  0.4   0.13  0.46     DENSITY  1.67    1.59    1.74  1.68  1.74  1.63     DENSITY, --      1.62    --    1.68  --    1.63     COR.     RESILIENCY              38      39      32    33    37    33     AIR FLOW 2.7     3.07    6.14  5.95  5.96  5.33     IFD.sub.-- THICK              4.07    4.06    4.05  4.05  3.99  4.02     IFD.sub.-- 25%              44.03   43.42   36.57 31.25 32.55 32.17     IFD.sub.-- 65%              89.18   85.05   71.93 64.27 65.93 64.72     RETURN.sub.--              72.91   74.27   72.08 72.06 72.58 74.59     VAL     IFD.sub.-- 65/25              2.03    1.96    1.97  2.06  2.03  2.01     TENSILE  10.56   13.61   10.21 13.15 12.3  12.23     ELON-    108.86  165.03  157.08                                    226.89                                          209.42                                                222.4     GATION     TEAR     1.09    1.22    1.13  1.75  1.52  2.3     COMP.sub.-- 90%              3.99    2.84    3.38  3.31  4.21  4.42     HA.sub.-- COMP.sub.--              4.48    3.77    --    --    --    --     75     WET.sub.-- SET.sub.--              2.34    2.51    2.73  3.05  3.83  3.59     50     ______________________________________

Having now fully described the invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the invention as set forth herein. 

What is claimed is:
 1. A polyurethane flexible foam comprising the reaction product of:a) an organic di- or polyisocyanate, at an isocyanate index of from about 70 to about 130; with b) a polyether polyol component comprising at least one polyoxyalkylene polyether polyol comprising the oxyalkylation product of an aqueous solution of one or more polyhydric, hydroxyl-functional solid initiators comprising a saccharide, polysaccharide, or derivative thereof, wherein the water content of said aqueous solution is between 12 weight percent and 90 weight percent relative to the weight of said aqueous solution, and wherein said polyoxyalkylene polyether polyol has a calculated functionality of between about 2.2 and 4.0 and a hydroxyl number between about 10 and about 180 in the presence of c) an effective amount of a urethane reaction-promoting catalyst; d) water as a reactive blowing agent in an amount effective to prepare a flexible foam having a density of between about 0.5 lb/ft³, and 6 lb/ft³ ; and optionally e) a cell-stabilizing amount of one or more surfactants.
 2. The polyurethane flexible foam of claim 1 further comprising a non-reactive blowing agent such that the density of said polyurethane flexible foam is between about 0.5 lb/ft³ and 3.5 lb/ft³.
 3. The polyurethane flexible foam of claim 1 wherein said isocyanate index is between about 85 and
 125. 4. The polyurethane flexible foam of claim 1 wherein said at least one polyoxyalkylene polyether polyol comprises a polyol having a calculated functionality between about 2.2 and 3.7 and a hydroxyl number between about 20 and about 60, prepared by oxyalkylating an aqueous solution comprising sorbitol and from about 12 weight percent to about 50 weight percent water. 